1. Field of the Invention
This invention relates to an ink jet recording apparatus. More particularly, the invention is concerned with a recording apparatus provided with an ink jet head generally called "full line multi-array orifice type ink jet head".
2. Description of Prior Art
Among various recording systems which are known at present, the so-called "ink jet recording system" is regarded as highly useful in realizing various types of recording apparatus such as printer, word processor, reproduction device, etc., because it is of a non-impact recording system which produces the least noise at the time of recording, and is capable of recording at a high speed on a plain paper without necessity for any fixing treatment to be effected thereon. So far, various proposals have been made on this ink jet recording system, some of which are already commercialized after having many improvements made to them, and others are still being developed for practical uses.
The ink jet recording system is to perform image recording by causing droplets of recording liquid (which will simply be referred to as "ink" throughout the specification) to fly, based on various operating principles, onto the surface of a recording material such as paper, etc. An ink droplet producing device (i.e., an ink jet device) for use in such an ink jet recording system consists generally of an ink jet head for forming the ink droplets and an ink feeding system for feeding ink to the head.
As a type of the ink jet head, there is one that is generally called "a single orifice type" or "a semi-multi-orifice type" head having one to ten, or so, of the ink discharging orifices. This type of head is relatively simple in its construction, easy to replace when the head is out of order or damaged, and not so expensive as the other recording systems. In addition, since the ink feeding system for this type of ink jet head has a lesser number of ink discharge orifices, hence less consumption of ink, it can be constructed relatively simply utilizing a simplified cartridge tank or a single ink feeding pipe.
However, when using a different type of the ink jet head (generally called "full line multi-array orifice type head") capable of printing a line on the recording paper almost instantaneously, the replacement of the head is not easy thereby to increasing the possibility of trouble, and damage to some part of the head. Moreover, from the economic aspect, the replacement of the entire head is limited. Besides, when using the full line multi-array orifice type head, it is necessary to maintain a constant space interval between the head and the surface of the recording paper over the full breadth thereof during the recording operation. In order to attain this objective, there, so far, has been required high mechanical precision and assembly precision as well as complicated accessory mechanisms and troublesome measures for preventing the head from ink contamination and protecting the head itself during stoppage of the recording apparatus. Furthermore, in order to drive the full line multi-array orifice type ink jet head, a large number of electrode lead wires, say 2,000 to 4,000, are required so that the overall structure of the device becomes complicated. To avoid such a complicated device, there is a way of driving the head in a time-divisional mode by assembling the lead wires in a matrix form. Even in this instance, however, it is indispensable to insert arrays of diodes and transistors between the head and the lead wires arranged in a matrix for the purpose of imparting the switching function and various other functions to the wiring. Such an expedient has also brought about inconvenience such that, due to reliability of these semiconductor elements, breakage of the wiring during operation, and so on, the entire head unit comprising the head, the wiring, and others should be replaced with a new one.